Electrical switches that are frequently used inevitably must be changed. If, for example, the switches are on a control panel for operating a giant machine, it is important that the "down time" of the machine be minimized when a faulty switch must be changed, the reason being that large, expensive machines may have operating values in the thousands of dollars per hour. With ordinary and well-known switches, the wiring time incident to changing the switch can result in a large monetary loss. However, if the switch can be changed in a matter of minutes, the loss is minimized. The principal object of the present invention is to provide a switch construction which minimizes the down time by reason of the fact that removal and replacement of the switch does not require the manual operation of disconnecting each wire leading to the switch and then reconnecting the wires to a replacement switch.
For example, assume that on such a machine it is either time for a periodic change of switches or that there is a switch failure. Locating and rewiring a faulty switch, particularly when exposed terminals may be corroded, rusted, etc., can be a slow and tedious process. Necessarily, during the course of this process the machine must be stopped. Using the present invention, the machine must be stopped only sufficiently long to permit a subassembly of switches to be unplugged and a replacement subassembly to be plugged in, without even stopping to determine which of the individual switches of the assembly may be causing difficulty. The switches of the subassembly are contained in a housing which ameliorates the problem of corrosion, rust, etc., on the electrical components.
In some machines the stopping of the machine will have a deleterious effect upon the process being carried out by the machine. For example, on an injection molding machine, the operating temperature of the machine during a production run is critical. Shutting the system down may adversely affect the tolerances of the parts produced thereby. Should an electrical switch on such a machine fail, it is important that the switch be immediately replaced so that the critical conditions are not adversely affected. This problem is solved by the use of the present invention since a spare subassembly of switches may be kept on hand and promptly exchanged for the subassembly which includes the defective switch, when a failure occurs.
A further feature of the present invention is that the switch units can be multiplied to meet the requirements of a particular machine. On one machine, for example, it may be required that a particular push-button actuates two switches while on another machine there may be a requirement for a pushbutton to actuate six switches. Through the use of the present invention, the same components may be "stacked" so as to increase the number of individual switches actuated by a single push-button.
Furthermore, the modular switches of the present invention reduce the inventory of spare switches that must be maintained.
Additional objects and advantages will become apparent from the following description.